A long standing problem in the area of international telecommunications and, more particularly, in the area of initiating and completing international phonecalls over public switched service voice networks has been that a considerable portion of the so-called system time, that is, the period between initiation of a phonecall and either completion thereof or determination that the call cannot be completed (because of a no answer or busy signal) is non-billable in nature. For example, billing-protocols, as they have evolved over time, both in the United States and abroad, only permit billing to the ultimate customer for the period between call completion and call termination as perceived by the ultimate customer. In other words, under such established billing protocols, the ultimate customer (as opposed to an intermediary such as a hotel or aggregator) cannot be charged for the system time required to ring the called location to determine if the call can be completed. Further, such phonecalls do not permit billing for the so-called disconnect time, that being the time between the termination of the phonecall as perceived by the caller and the actual stand down or reset time by the public switched service network.
The prior art use of system time in such a non-productive fashion has also operated to limit total usable system capacity in areas where trunk, channel or bandwidth capacity is finite, as in third world situations and in satellite transception.
To minimize such non-billable system time and, as well, to effect other advantages, the development of so-called call back technology, also known as reverse direction phonecalling, has developed. In callback technology, a so-called network control module induces a callback from a central switching station associated with the called location. This call-back procedure has the advantage not only of reducing unbillable system time inasmuch as a callback will not be initiated if the called location is unreachable but, as well, to effect considerable saving in call cost by virtue of the fact that call cost from Location A to Location B typically does not equal call cost from Location B to Location A, this being particularly the case in international phone communications.
The technology of point-to-point reverse direction phonecalling, both for purposes of minimizing system time and for purposes of minimizing call cost based upon the directionality of the call, is well developed in the art, as is exemplified by U.S. Pat. No. 5,027,387 (1991) to Moll, entitled Reverse Direction Calling System.
Such reverse direction calling technology has, however, not been universally available. For example, in a hotel environment, a guest at the hotel has no means of answering a callback directly since the callback must be received by an operator that must know in advance who the call is for and where to transfer it to. This difficulty, plus other factors relative to billing procedures in hotels, has prevented most major hotels from employing international callback services. Similar problems are encountered by other large facilities such as hospitals, industrial installations, governmental sites and telephone companies themselves.
A further limitation in the art of callback technology has existed in the area of teleconferencing of international calls in which, for reasons of reduction of system time use and avoidance of phone charges by high priced national phone companies, it is desirable to route a call, from a first foreign country to a second foreign country, through a third foreign country (known as transit country) typically the United States, Canada or United Kingdom, to avoid the typically high country-to-country charge between the first and second countries. For example, in situations where call supervision exists, it is generally cost-effective to reconfigure what would otherwise be a call from Country A to Country B into the form of teleconferencing of two separate calls, namely, a call from Country C (typically the U.S.) to Country A, with a call from Country C to Country B. This procedure will, because of the high cost of calls originated from Country A, be less than the cost of a direct dialed Country A to Country B phonecall. In other words, where all legs of the CA and CB phonecalls are completed, the total cost of the teleconferenced CA and CB calls is less than the cost of the direct dialed Country A to Country B cost would have been.
The problem, however, with such callback and teleconferencing procedures has been that in situations where either or both the CA and CB legs of the teleconference cannot be completed because, for example, of a busy or no answer at Locations A or B, the provider of the international callback service must absorb the cost of the system time associated with interrogating locations in Countries A and B in attempting to complete the CA and CB legs of the phonecall. As such, the international reverse callback procedure can involve considerable losses to the callback operator which can only be recovered by increasing the price charged for completed calls.
Another problem in international callback that can increase cost to the operator is that of reverse answer supervision after a call termination, or the lack thereof. That is, without a call completion signal transmitted back from the calling location to the transit country switch after call termination, it can-be difficult for the transit switch (in Country C) to know when a call is finished. This issue can have devastating consequences to the callback operator.
The instant invention provides a solution to the above problems and, additionally, provides a means by which hotels, and other similarly situated establishments, can make use of international callback technology and, further, can do so on a more profitable basis than has been available to any prior user of such technology. The present invention also addresses problems of billing to intermediaries and end users of callback facilities.
The present novel method of use of a public telecommunications voice network (typically a public switched service network) includes the steps of assigning a caller identification number to a calling location and of assigning a called party identification number for the location to be called. Thereafter, use is made of a transparent communications node, associated with the calling location, which transmits said caller and called party identification and security numbers to a central switching unit in the nature of a digital tandem ISDN switch or private line data service which is associated with the called location. Said transmission of caller and called party identification number to the central switching unit proceeds through a data signalling channel independent of the public telecommunications voice network. Said central switching unit is then employed to interrogate the called location to obtain the call supervision status thereof. If said call status is that of an answer, said central switching unit will complete a first phonecall from said unit to the called location and will originate a second phonecall through the telecommunications network to the calling location. Upon completion of both phonecalls, they are teleconferenced, thereby placing the calling and called parties in communication with each other. However, if said call status at the called location is that of a no answer or busy, an uncompleted call status signal is provided to the central switching unit. Thereafter, the central switching unit may either transmit a call status signal through said independent signalling channel to the local communications node to inform the calling location that the call cannot be completed or, alternatively, the central switching unit may not send any status signal whatsoever to the local communications node. Therein, a predetermined interval of silence from the central switching unit will be interpreted by the local communications node to mean that the call could not be completed. An appropriate advisory will be sent to the calling party. Upon termination of the second phonecall, an answer supervision signal is sent by the local node to the central switching unit.
It is, accordingly, an object of the present invention to provide an improved method and system of telecommunications network use which will operate to reduce system time and operator cost associated with teleconferencing of international calls involving at least one reverse direction phonecall.
It is another object to provide a system of the above type that will increase the efficiency of use of telecommunication resources.
It is a further object to provide a method which will reduce the cost of collect and person-to-person long distance phonecalls.
It is a yet further object to provide a system of the above type usable in connection with multi-trunk switching.
It is a still further object to provide an improved method of telecommunication network use which will enlarge the potential application of reverse direction telephone calling to areas, such as hotel and telephone company use, in which it has not heretofore been usable.
It is another object to provide a system of the above type having reverse answer detection after call termination.
The above and yet other objects and advantages of the present invention will become apparent from the hereinafter set forth Brief Description of the Drawings, Detailed Description of the Invention and Claims appended herewith.